Sulfur in coke: Sulfur is one of the harmful impurities in pig iron smelting, which reduces the quality of pig iron. In the steelmaking pig iron, the sulfur content is more than 0.07%, which is waste. 13% of the sulfur brought into the furnace from the blast furnace charge comes from the ore; 3.5% comes from limestone; 82.5% comes from coke, so coke is the main source of sulfur in the charge. The level of coke sulfur directly affects the production of blast furnace iron. When the coke sulfur content is greater than 1.6%, the sulfur content increases by 0.1%, the coke usage increases by 1.8%, the limestone addition increases by 3.7%, the ore addition increases by 0.3%, and the blast furnace output decreases by 1.5-2.0%. Not more than 1%, the metallurgical coke used in large and medium sized blast furnaces has a sulfur content of less than 0.4-0.8%.